Gotta love David Hathaway. A candid admission of the inability of his take on the solar dynamo theory to make successful predictions is refreshing. Good to see such honesty from the dynamologist in Cheif.
You’re listening to SCIENCE FRIDAY from NPR. I’m Ira Flatow.
Up next, a look at the action on the sun. Scientists who study the sun say it’s been acting a little bit strange lately. The sun has cycles, periods of high activity, when it has lots of sunspots, or low activity when things on the surface seem pretty calm. And based on previous sun activity, researchers expected that the sun would soon be entering a stretch of high activity, but that doesn’t seem to be the case.
The next peak, expected in 2013, seems to be off to a weak start, and scientists are not sure why. Predicting the sun’s activity has never been a precise science. It’s more like predicting the weather. And you can be pretty sure about some of the basics, but the devil, as they say, is in the details.
Joining me now to tell us more about it is my guest, David H. Hathaway. He’s a solar astronomer at NASA’s Marshall Space Flight Center in Huntsville, Alabama. Welcome to SCIENCE FRIDAY, Dr. Hathaway.
Dr. DAVID H. HATHAWAY (Marshall Space Flight Center): Oh, thank you, Ira. That was well-put for the intro.
(Soundbite of laughter)
FLATOW: I usually get them wrong.
Dr. HATHAWAY: No, no. That was quite on target.
FLATOW: Tell us what the – what – is it just sunspot activity that creates, you know, the cycles or is there other activity going on?
Dr. HATHAWAY: Oh, there’s other activity. It’s just the sunspots are the most obvious manifestation, and we’ve been able to observe sunspots reliably and almost on a daily basis since Galileo’s time in 1610. But with the sunspots comes the various things that we call space weather. There are solar flares, which are huge explosions on the surface of the sun, energy equivalent at the million megatons of TNT. And there are coronal mass ejections, where literally a billion tons of matter are blown off the sun and thrown to the solar system at a million miles an hour.
And that stuff impacts us – in particular our assets in space, but even does things here on the ground. It helps produce the aurora borealis, which is kind of nice but can do nasty things like sending a surge of current from power lines that takes out transformers and flips circuit breakers so people are without power.
FLATOW: Yeah, I hate it when that happens.
Dr. HATHAWAY: Yeah, yeah. So do I, especially in the summer.
FLATOW: So are there really set cycles the sun goes through? Why does it go through these cycles? Why isn’t it just stable?
Dr. HATHAWAY: Oh, yeah, great question. I wish I knew the answer. It goes through a cycle of about 11 years with sunspots, but again, about 11 years, it varies by, give or take, about one year. And the thing that really surprised us this time is that the last cycle, it took 12 years and three months before the next cycle really got started. And that’s -the late start is indicative of a small cycle, but it’s all related to magnetism, magnetic fields generated within the sun. That much we know for sure. The precise details on how it does that or – is, again, where the devil is. But we’re learning more about it.
We’re sure of some aspects as far as how flows within the sun take the magnetic fields and drag them around and stretch them out and twist them up. But for the last decade, I thought we had it figured out, until this sunspot cycle minimum came around and there were a number of unexpected things that makes me believe that at least my understanding of how it worked, that I thought was correct for the last 10 years, is in error. So we were – it’s…
FLATOW: So we thought we knew how the sun works, but we’re not quite sure.
Dr. HATHAWAY: Yeah, certainly I’m not.
(Soundbite of laughter)
Dr. HATHAWAY: It’s job security in some sense.
(Soundbite of laughter)
FLATOW: Time for another sun probe or something.
Dr. HATHAWAY: Oh, well, we just launched, in fact, the Solar Dynamics Observatory, which comes at a great time, and certainly as far as the sun misbehaving like this. And again, we’re seeing low levels of activity that we have not seen in about 100 years.
FLATOW: In a hundred years, really, that long?
Dr. HATHAWAY: That’s right, yeah. And the sun tends to go through these longer cycles like that. Again, there’s an 11-year cycle of activity, but there are big cycles and small cycles, and they tend to grow and then get small again. There’s about 100-year periodicity in that, that at the beginning of the 20th century we had a couple of small sunspots cycles. And at the beginning of the 19th century we had two really small cycles.
The beginning of the 18th century, we were just coming out the period of 70 years without sunspots, where it’s been called the Maunder Minimum.
Dr. HATHAWAY: So it – we have times like that, but as far as what we’re seeing for recent activity, what we’re expecting for the peak of activity in 2013 is you got to go back about 100 years to find similar sorts of activity from the sun.
FLATOW: When the sun is quiet like this, does it come back with a vengeance, or just normal?
Dr. HATHAWAY: Well, it’ll take another 50 years, apparently. But it may be longer. In fact, a number of my colleagues have suggested that perhaps, or certainly there’s the possibility that we are heading into another one of these long, grand minima like the Maunder Minimum. You know, the Maunder Minimum from the year 1645 to 1715, and it was 70 years, virtually, without sunspots. There were a few that started taking up near the end. But, basically, as far as sun spots, the sun stopped doing it for 70 years.
FLATOW: Did it affect the Earth any way we could tell?
Dr. HATHAWAY: Yeah. It comes at the end of what is called the Little Ice Age for climate. And both that minimum and the minimum at the beginning of the 19th century correspond to cool times in Earth’s climate. It has led us to believe that the sun does – the solar variability, I should say, this, you know, coming and going of sunspot cycles – does influence climate to some extent. And the big question is to how big an extent. And there’s a wide range of feelings on what that is.
The best analyses I’ve seen suggest that the sun’s still a minor player, that it’s really the anthropogenic forcing that’s overwhelming things now, and that even if the sun did go into one of these long, extended periods of no activity, it wouldn’t save us from global warming.
Dr. HATHAWAY: Yeah. Yeah. There’s people that were betting on it, but I wouldn’t.
FLATOW: Are they related to space junk? I heard that they are. Is that right?
Dr. HATHAWAY: Well, space – well, a big cycle is good for space junk, because when the sun is particularly active, it puts out a lot of excess ultraviolet light and x-rays. And that heats up the Earth’s uppermost atmosphere. In fact, spacecraft altitudes makes the atmosphere, you know, expand, and so the density at the altitude where a lot of space junk is will go up when the sun’s most activity. And that helps to clear out the space junk as far as it causes drag on the space junk and it slowly spirals in and burns up in the Earth’s atmosphere. So, a small cycle isn’t good news for getting rid of space junk, but it is good news as far as the damage that solar activity does to electronics in space…
Dr. HATHAWAY:…and the possibility of power outages and communication outages here on the ground.
FLATOW: Well, that’s also good news to ham radio operators and people like that because the sun spots…
Dr. HATHAWAY: The ham radio operators like a big cycle. In fact, they’re really upset with me that – well, because I went out on a limb back in 2006 using a solar cycle prediction technique that relied on us being near sunspot cycle minimum. And I thought, well, the last few cycles were 10-year cycles. Chances are the next one will be a 10-year cycle. So I went out on a limb and made a prediction in 2006 that I have long since regretted, but it was a prediction there was going to be a big cycle coming up. I’ve now, at every opportunity, recant that prediction, but the ham radio operators, they’re saying you promised us.
Dr. HATHAWAY: Well, sorry guys.
FLATOW: Yeah. Well, you know, now, just stand in line with all the weather forecasters.
Dr. HATHAWAY: I know how they feel. I really do, as far as, you know, when you – in fact, there’s a great quote that, you know, prediction is difficult, especially about the future, that – and it is. When you’re really making a prediction about something that’s, you know, hasn’t happened yet and people are depending upon that prediction, yeah.
FLATOW: Well, lets put you on the record again. What are you going to predict now for…
Dr. HATHAWAY: I’m predicting that the sunspot number, which is basically the number of sunspots on an average day in about June or July of 2013, will only be about 65 or so. And that’s about half as big a cycle as what we had that peaked back in the year 2000, and only about a third of what we had for two cycles before that. So, much smaller than recent activity that we’ve seen in the last – well, during the Space Age. I mean, this is…
Dr. HATHAWAY: …tiny compared to what we’ve – we’re used to with the Space Age.
FLATOW: I wonder if the British bookies make bets on these.
Dr. HATHAWAY: I actually had a guy who got upset when I didn’t put out my sunspot number stuff on a daily basis, because he was using it to predict the stock market. And he kept coming to me for couple years, and I haven’t heard from him in a long time. So I don’t think it worked.
FLATOW: To predict – well, it’s as good as anything else, throwing darts, right?
Dr. HATHAWAY: It may be. But like I said, he stopped calling me, so I’m assuming that he realized this didn’t work. I lost a bunch of money on this guy.
(Soundbite of laughter)
FLATOW: All right. Well, at least we have you on the record with a new prediction. You’re saying it’s going to be about half the number.
Dr. HATHAWAY: It’ll be about half what it was for the last sunspot cycle, the one that peaked in the year 2000. About July of 2000 was the last sunspot number peak, and that was 120, 121 or so for sunspot number. And it – you know, my prediction, as of this morning, is – I think a 64 is what it came out at. And it’s actually – it’s been declining. Someone…
FLATOW: Yeah. Well, it’s not a safe thing for us ourselves to look at the sun to try to count them. But I’m sure on…
Dr. HATHAWAY: No. No.
FLATOW: …on the Web…
Dr. HATHAWAY: In fact, the people that do it actually project – use a telescope, but project it onto a sheet of paper…
Dr. HATHAWAY: …project the image onto a sheet of paper and actually draw on the sheet of paper. And that was the way it was done, you know, back in Galileo’s time…
Dr. HATHAWAY: …that it was by projection.
FLATOW: Is there a sunspot place on the Web to keep the number changes every day, you could watch it?
Dr. HATHAWAY: There’s – spaceweather.com does sunspot numbers every day.
Dr. HATHAWAY: The problem is that the people who have the official international sunspot number only come out once a month with it.
FLATOW: All right. We’ll have to do it on a monthly basis, then. I want to thank you for taking time to be with us. And we’re going to be watching your prediction, David.
Dr. HATHAWAY: Oh, I’m planning on it.
(Soundbite of laughter)
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